Originally Posted by
kchoya
This post doesn't make sense. Most (if not almost all) car seats are approved by the FAA to be secured facing forward or facing the rear.
Can't speak to the current FAA rules but there are a great number of seats, probably most of them, designed to be used only one direction because of the angle of incline and method of strap attachment.
Back in the day my kid had a seat designed to be convertible, and converting it was not simple. You basically had to take it apart and rethread the straps and then reassemble the bucket/cushion section. I went to a class that explained the physics of all this when I was pregnant, and the instructor did crash mock-ups to show the differences. To face one direction the straps should originate below the child's shoulders and for the other direction they should be from above. Don't ask me which is which anymore; my kid is old enough for a driver's license of his own now.
Angle of incline matters, too. Put a child with poor head control in a seat that is too upright and the child may compress their airway and basically suffocate.